Update documentation for dynamic buffer resizing.

README.md

@@ -14,7 +14,8 @@ Full API documentation is available here: http://pubsubclient.knolleary.net
 
  - It can only publish QoS 0 messages. It can subscribe at QoS 0 or QoS 1.
  - The maximum message size, including header, is **128 bytes** by default. This
-   is configurable via `MQTT_MAX_PACKET_SIZE` in `PubSubClient.h`.
+   is configurable via `MQTT_MAX_PACKET_SIZE` in `PubSubClient.h` or at runtime
+   using PubSubClient::setBufferSize().
  - The keepalive interval is set to 15 seconds by default. This is configurable
    via `MQTT_KEEPALIVE` in `PubSubClient.h`.
  - The client uses MQTT 3.1.1 by default. It can be changed to use MQTT 3.1 by

examples/mqtt_auth/mqtt_auth.ino

@@ -27,9 +27,9 @@ void setup()
 {
   Ethernet.begin(mac, ip);
   // Note - the default maximum packet size is 128 bytes. If the
-  // combined length of clientId, username and password exceed this,
-  // you will need to increase the value of MQTT_MAX_PACKET_SIZE in
-  // PubSubClient.h
+  // combined length of clientId, username and password exceed this use the
+  // following to increase the buffer size:
+  // client.setBufferSize(255);
   
   if (client.connect("arduinoClient", "testuser", "testpass")) {
     client.publish("outTopic","hello world");